You don’t need to update a site or tour because google will still see it as a nice active site if you just get one or two links to it a week. When you stop getting links then you need to start updating the site.
Blogs work well because they always have new content. IOW new posts so the SE keep coming back to them to see what else is new. If you post to your blog often enough the SE will come by many times a day.
However if you stop posting they will stop coming. Same with a site. As soon as you quit adding new things the SE stop coming. That’s not really what you want, is it? A stagnant site just doesn’t get much exposure in the serps.
What if I told you there was a very easy and very quick way to keep your site on top of the serps for whatever terms you choose? Would that interest you at all? Cool, go deposit 5 bucks in my paypal account and I’ll tell you. 
In the meantime go check out some the hot porn sites that are listed in other posts.